Viewing archive of Wednesday, 17 December 2025
Solar activity report
Report of Solar-Geophysical Activity 2025 Dec 17 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 351 Issued at 2200Z on 17 Dec 2025IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z Solar activity has been at low levels for the past 24 hours.
There are currently 5 numbered sunspot regions on the disk.
IB. Solar Activity Forecast
Solar activity is expected to be low with
a slight chance for an M-class flare on days one, two, and three (18
Dec, 19 Dec, 20 Dec).
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 744 km/s at 17/2030Z. Total IMF reached 8
nT at 17/1801Z. The maximum southward component of Bz reached -7 nT at
17/1241Z. Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 1632 pfu.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected
to be at quiet to active levels on day one (18 Dec) and quiet to
unsettled levels on days two and three (19 Dec, 20 Dec).
III. Event Probabilities 18 Dec to 20 Dec
| Class M | 15% | 15% | 15% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 17 Dec 119 Predicted 18 Dec-20 Dec 118/115/110 90 Day Mean 17 Dec 150
V. Geomagnetic A Indices
Observed Afr/Ap 16 Dec 006/012 Estimated Afr/Ap 17 Dec 010/014 Predicted Afr/Ap 18 Dec-20 Dec 014/015-009/010-008/008
VI. Geomagnetic Activity Probabilities 18 Dec to 20 Dec
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 35% | 25% | 20% |
| Minor storm | 15% | 10% | 05% |
| Major-severe storm | 05% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 10% | 15% | 15% |
| Minor storm | 25% | 25% | 25% |
| Major-severe storm | 50% | 35% | 25% |
All times in UTC
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Space weather facts
| Last X-flare | 2025/12/08 | X1.1 |
| Last M-flare | 2025/12/31 | M7.11 |
| Last geomagnetic storm | 2026/01/02 | Kp5 (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| December 2025 | 124 +32.2 |
| January 2026 | 112.1 -11.9 |
| Last 30 days | 105.6 -3.7 |